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Windows 7Operating system · Microsoft

CVE-2014-6321

HIGH · 10.0 CVSS v2.0 Published 2014-11-11
Patch available
A vendor patch is available. No clean upgrade release — apply the published patch.
See remediation →
100/100
Remediation priority · Urgent
High EPSS Public exploit Remotely reachable No privileges Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Schannel in Microsoft Windows Server 2003 SP2, Windows Vista SP2, Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Windows 8, Windows 8.1, Windows Server 2012 Gold and R2, and Windows RT Gold and 8.1 allows remote attackers to execute arbitrary code via crafted packets, aka "Microsoft Schannel Remote Code Execution Vulnerability."

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A remote code execution vulnerability in Microsoft's Schannel (Security Channel) cryptographic library allows unauthenticated remote attackers to execute arbitrary code via specially crafted packets. The vulnerability affects the SSL/TLS implementation in multiple Windows versions.

MitigationApply the relevant Microsoft security update (MS14-066) to all affected Windows systems, or upgrade to a Windows version that includes the fix. Verify SSL/TLS functionality after patching.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Windows 7Operating system
Affected:all versions
Windows 8Operating system
Affected:all versions
Windows 8.1Operating system
Affected:all versions
Windows RtOperating system
Affected:all versions
Windows Rt 8.1Operating system
Affected:all versions
Windows Server 2003Operating system
Affected:all versions
Windows Server 2008Operating system
Affected:all versions= r2
Windows Server 2012Operating system
Affected:all versions= r2

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Authentication
None
Confidentiality
Complete
Integrity
Complete
Availability
Complete

AV:N/AC:L/Au:N/C:C/I:C/A:C

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify Windows version
    Run 'winver' from command prompt or check System Properties to confirm the exact Windows version and build number
    Affected if The system runs Windows 7, Windows 8, Windows 8.1, Windows RT, Windows RT 8.1, Windows Server 2003, Windows Server 2008, Windows Server 2008 R2, Windows Server 2012, or Windows Server 2012 R2 without the MS14-066 update installed
  2. Verify MS14-066 security update installation
    Open Control Panel > Programs and Features > View installed updates, or run 'wmic qfe list' from command prompt, and search for update KB2999226 or any MS14-066 related security update
    Affected if The security update from MS14-066 is NOT listed among installed updates
  3. Confirm Schannel SSL/TLS is in use
    Check that the system is configured to use Schannel for SSL/TLS by reviewing enabled protocols in Windows Registry under HKLM\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL, or verify the system accepts HTTPS/TLS connections
    Affected if Schannel is the enabled security provider and the system accepts SSL/TLS connections on any port (this is the default configuration)

If the system runs any affected Windows version listed and the MS14-066 security update is NOT installed, the environment is vulnerable to remote code execution via the Schannel flaw.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Patch available Apply the vendor patch
Vendor patch docs.microsoft.com →
Interim mitigation

Apply the relevant Microsoft security update (MS14-066) to all affected Windows systems, or upgrade to a Windows version that includes the fix. Verify SSL/TLS functionality after patching.

Recommended fix High confidence
  1. Apply Microsoft Security Bulletin MS14-066, which patches the Schannel remote code execution vulnerability (CVE-2014-6321)
  2. Obtain the update from https://docs.microsoft.com/en-us/security-updates/securitybulletins/2014/ms14-066
  3. Install the appropriate update for your Windows version: KB2999226 (Universal) or the specific KB listed in the bulletin for your OS
  4. Restart the affected system after applying the update to ensure the Schannel security update takes effect
  5. Verify the update was successfully installed by checking Windows Update history or the installed updates list

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Windows 7 Scoped from the published advisory
  • Consultation4.0 h
  • Implementation16.0 h
  • Testing8.0 h
  • Review / QA4.0 h
32.0 hours of engineering $5,600
Get the patch applied

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $8,960.

Scan for this in your stack

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2014-6321 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data